diff --git a/full-backend-tests/src/test/java/org/graylog2/indexer/indices/IndicesIT.java b/full-backend-tests/src/test/java/org/graylog2/indexer/indices/IndicesIT.java
index 6c87b6399d95a..e14480ad5ad66 100644
--- a/full-backend-tests/src/test/java/org/graylog2/indexer/indices/IndicesIT.java
+++ b/full-backend-tests/src/test/java/org/graylog2/indexer/indices/IndicesIT.java
@@ -87,7 +87,7 @@ public class IndicesIT extends ContainerMatrixElasticsearchBaseTest {
             .id("index-set-1")
             .title("Index set 1")
             .description("For testing")
-            .indexPrefix("graylog")
+            .indexPrefix("test_index_set")
             .creationDate(ZonedDateTime.now())
             .shards(1)
             .replicas(0)
@@ -103,7 +103,6 @@ public class IndicesIT extends ContainerMatrixElasticsearchBaseTest {
     protected static final IndexSet indexSet = new TestIndexSet(indexSetConfig);
     private final Set<String> indicesToCleanUp = new HashSet<>();
     protected Indices indices;
-    @SuppressWarnings("UnstableApiUsage")
     private EventBus eventBus;
     private final NodeId nodeId = new SimpleNodeId("5ca1ab1e-0000-4000-a000-000000000000");
 
@@ -121,7 +120,6 @@ protected Map<String, Object> createTemplateFor(String indexWildcard, Map<String
 
     @BeforeEach
     public void setUp() {
-        //noinspection UnstableApiUsage
         eventBus = new EventBus("indices-test");
         final Node node = new Node(searchServer().adapters().nodeAdapter());
         final IndexMappingFactory indexMappingFactory = new IndexMappingFactory(node,
@@ -274,9 +272,7 @@ public void indexRangeStatsThrowsExceptionIfIndexIsClosed() {
 
     @ContainerMatrixTest
     public void indexRangeStatsThrowsExceptionIfIndexDoesNotExists() {
-        assertThrows(IndexNotFoundException.class, () -> {
-            indices.indexRangeStatsOfIndex("does-not-exist");
-        });
+        assertThrows(IndexNotFoundException.class, () -> indices.indexRangeStatsOfIndex("does-not-exist"));
     }
 
     @ContainerMatrixTest
@@ -306,7 +302,7 @@ public void createOverwritesIndexTemplate() {
                 "properties", ImmutableMap.of("message",
                         ImmutableMap.of("type", "text")));
 
-        var templateSource = Template.create(indexSet.getIndexWildcard(), new Template.Mappings(beforeMapping), 0L, new Template.Settings(Map.of()));
+        var templateSource = Template.create(indexSet.getIndexWildcard(), new Template.Mappings(beforeMapping), 1L, new Template.Settings(Map.of()));
 
         client().putTemplate(templateName, templateSource);
 
@@ -409,7 +405,7 @@ public void ensureIndexTemplateThrowsOnIgnoreIndexTemplateAndNonExistingTemplate
 
         try {
             indices.deleteIndexTemplate(indexSet);
-        } catch (Exception e) {
+        } catch (Exception ignored) {
         }
 
         assertThat(client().templateExists(templateName)).isFalse();
@@ -651,7 +647,6 @@ public void cyclingAliasLeavesOldIndexInPlace() {
         assertThat(indices.exists(index1)).isTrue();
     }
 
-    @SuppressWarnings("UnstableApiUsage")
     public static final class IndicesEventListener {
         final List<IndicesClosedEvent> indicesClosedEvents = Collections.synchronizedList(new ArrayList<>());
         final List<IndicesDeletedEvent> indicesDeletedEvents = Collections.synchronizedList(new ArrayList<>());
diff --git a/graylog-storage-opensearch2/src/test/java/org/graylog/storage/opensearch2/testing/ClientOS2.java b/graylog-storage-opensearch2/src/test/java/org/graylog/storage/opensearch2/testing/ClientOS2.java
index 806c5b78f2cca..af85505382de1 100644
--- a/graylog-storage-opensearch2/src/test/java/org/graylog/storage/opensearch2/testing/ClientOS2.java
+++ b/graylog-storage-opensearch2/src/test/java/org/graylog/storage/opensearch2/testing/ClientOS2.java
@@ -40,8 +40,6 @@
 import org.graylog.shaded.opensearch2.org.opensearch.client.indices.DeleteComposableIndexTemplateRequest;
 import org.graylog.shaded.opensearch2.org.opensearch.client.indices.GetComposableIndexTemplateRequest;
 import org.graylog.shaded.opensearch2.org.opensearch.client.indices.GetIndexRequest;
-import org.graylog.shaded.opensearch2.org.opensearch.client.indices.GetIndexTemplatesRequest;
-import org.graylog.shaded.opensearch2.org.opensearch.client.indices.GetIndexTemplatesResponse;
 import org.graylog.shaded.opensearch2.org.opensearch.client.indices.GetMappingsRequest;
 import org.graylog.shaded.opensearch2.org.opensearch.client.indices.GetMappingsResponse;
 import org.graylog.shaded.opensearch2.org.opensearch.client.indices.PutComposableIndexTemplateRequest;
@@ -164,11 +162,12 @@ private Stream<Map.Entry<String, JsonNode>> extractFieldMappings(String index, J
 
     @Override
     public boolean templateExists(String templateName) {
-        final GetIndexTemplatesRequest request = new GetIndexTemplatesRequest("*");
-        final GetIndexTemplatesResponse result = client.execute((c, requestOptions) -> c.indices().getIndexTemplate(request, requestOptions));
+        var request = new GetComposableIndexTemplateRequest("");
+        var result = client.execute((c, requestOptions) -> c.indices().getIndexTemplate(request, requestOptions));
         return result.getIndexTemplates()
+                .keySet()
                 .stream()
-                .anyMatch(indexTemplate -> indexTemplate.name().equals(templateName));
+                .anyMatch(indexTemplate -> indexTemplate.equals(templateName));
     }
 
     @Override
diff --git a/graylog2-server/src/test/java/org/graylog/testing/elasticsearch/ContainerMatrixElasticsearchBaseTest.java b/graylog2-server/src/test/java/org/graylog/testing/elasticsearch/ContainerMatrixElasticsearchBaseTest.java
index 05cc68c2aa50a..d309d4ab05bb1 100644
--- a/graylog2-server/src/test/java/org/graylog/testing/elasticsearch/ContainerMatrixElasticsearchBaseTest.java
+++ b/graylog2-server/src/test/java/org/graylog/testing/elasticsearch/ContainerMatrixElasticsearchBaseTest.java
@@ -59,7 +59,7 @@ private void addGraylogDefaultIndexTemplate() {
     private static Map<String, Template> getGraylogDefaultMessageTemplates(SearchVersion version) {
         var template =
                 new MessageIndexTemplateProvider().create(version, null)
-                        .messageTemplate("*", "standard", 1L);
+                        .messageTemplate("*", "standard", 100L);
         return Collections.singletonMap("graylog-test-internal", template);
     }
 
diff --git a/graylog2-server/src/test/java/org/graylog/testing/elasticsearch/ElasticsearchBaseTest.java b/graylog2-server/src/test/java/org/graylog/testing/elasticsearch/ElasticsearchBaseTest.java
index ea5ad7776ca31..655a8b211e455 100644
--- a/graylog2-server/src/test/java/org/graylog/testing/elasticsearch/ElasticsearchBaseTest.java
+++ b/graylog2-server/src/test/java/org/graylog/testing/elasticsearch/ElasticsearchBaseTest.java
@@ -53,7 +53,7 @@ private void addGraylogDefaultIndexTemplate() {
 
     private static Map<String, Template> getGraylogDefaultMessageTemplates(SearchVersion version) {
         var template = new MessageIndexTemplateProvider().create(version, null)
-                .messageTemplate("*", "standard", 0L);
+                .messageTemplate("*", "standard", 100L);
         return Collections.singletonMap("graylog-test-internal", template);
     }